Consider debug info intrinsics pointing to null value as dead instructions.

llvm-svn: 127922

1 files changed, 14 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index e54dfb3dc73..19b999722db 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -211,7 +211,20 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
 bool llvm::isInstructionTriviallyDead(Instruction *I) {
   if (!I->use_empty() || isa<TerminatorInst>(I)) return false;
 
-  // We don't want debug info removed by anything this general.
+  // We don't want debug info removed by anything this general, unless
+  // debug info is empty.
+  if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(I)) {
+    if (DDI->getAddress()) 
+      return false;
+    else
+      return true;
+  } else if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(I)) {
+    if (DVI->getValue())
+      return false;
+    else
+      return true;
+  }
+
   if (isa<DbgInfoIntrinsic>(I)) return false;
 
   if (!I->mayHaveSideEffects()) return true;